In order to explore the nature and extent of paternally-mediated reproductive events in humans, we propose to contract with the University of Bristol in order to purchase a data set which would allow us to look for associations between father's exposures and pregnancy outcome. The Avon Longitudinal Study of Pregnancy and Children is a population study of 10,000 pregnancies, in which data on important characteristics and exposures is available from the mothers and fathers as well as clinical data on the outcomes of the pregnancy and on the offspring.